The food matrix properties influence the antibacterial effectiveness of photodynamic and sonodynamic treatments

In this study, we established simulated food matrices to demonstrate that changes in the attributes such as transparency (by adding food coloring) and viscosity (by adding thickener) significantly influenced the efficiency of curcumin-mediated photodynamic treatment (blue light at 9.54 J/cm2 for 30 min) and sonodynamic treatment (45 kHz ultrasound at 0.40 W/cm2 for 30 min), respectively. Specifically, addition of 0.008% lemon-yellow pigment resulted in the absorbance increasing up to 3.24 with diminished bactericidal effects of photodynamic treatment (3 to 1.4 log CFU/mL reduction) against Staphylococcus aureus CICC 10201; while addition of 1.2% carboxymethyl cellulose increased viscosity from 0.004 to 2.482 Pa·S with decreased efficiency of sonodynamic treatment (1.5 to 0.1 log CFU/mL reduction). Our findings also indicated photodynamic treatment exhibited notably higher bactericidal efficacy (P < 0.05) for transparent but sticky foods such as ice jelly. These results underscored the importance of considering food matrix properties before application of photo-sonodynamic treatment. Industrial relevance: The photodynamic treatment and sonodynamic treatment are believed as promising and innovative non-thermal bacterial inactivation methods for food industry. Herein, we successfully demonstrated that the attributes of food matrix such as transparency and viscosity could significantly influence the efficiency of photodynamic treatment and sonodynamic treatment, respectively. Consequently, our findings may advance the proposition within the food industry that the properties of food matrix should be taken into consideration before application of photodynamic or sonodynamic treatments for food antimicrobial processing.